<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			var x = 10;
			function fn(){
				console.log(x);
			}
			function show(f){
				var x = 20;
				f();
			}
			show(fn);//10
		</script>
	</body>
</html>
